環(huán)境生態(tài)學(xué)---第五章溫度與代謝(已修改)
2024-10-28 01:36 本頁(yè)面
【正文】 E1 溫度與代謝 要 點(diǎn) 恒溫動(dòng)物和變溫動(dòng)物 按照有機(jī)體的體溫調(diào)節(jié)過(guò)程有可能對(duì)有機(jī)體進(jìn)行分類。一種可能的劃分是恒溫動(dòng)物和變溫動(dòng)物。當(dāng)環(huán)境溫度升高時(shí)，恒溫動(dòng)物保持著大致恒定的體溫，而變溫動(dòng)物的體溫隨環(huán)境溫度而改變。這種分類的一個(gè)問(wèn)題是，即使是典型的恒溫動(dòng)物也經(jīng)歷了降低體溫的時(shí)期。在有機(jī)體之間，可供選擇的另一種劃分如下描述。 恒溫動(dòng)物 變溫動(dòng)物 Ectotherms are anisms such as plants, reptiles and protista which are largely reliant on external sources of heat to raise their body are anisms capable of generating heat internally in order to raise their body temperature. Birds and mammals make up this group. The thermoneutral zone is the range of enmironmental temperatures in which an endotherm has only to exert a minimum metabolic effort in order to maintain a constant body temperature. The further away from the thermoneutral zone that the environmental temperature moves, the more energy the endotherm has to expend to maintain body temperature. Ectotherms and endotherms 外溫動(dòng)物和內(nèi)溫動(dòng)物 像爬行動(dòng)物等有機(jī)體屬外溫動(dòng)物，它們很大程度地依賴于外來(lái)的熱來(lái)提高自己的體溫。內(nèi)溫動(dòng)物是能夠在體內(nèi)產(chǎn)熱以升高體溫的有機(jī)體。鳥(niǎo)和哺乳動(dòng)物屬于這一類。 熱中性區(qū) （ thermoneutral zone）是環(huán)境的溫度范圍，在這個(gè)溫度范圍內(nèi)，內(nèi)溫動(dòng)物僅使用一個(gè)最小的代謝率以維持恒定的體溫。環(huán)境溫度離熱中性區(qū)越遠(yuǎn)，內(nèi)溫動(dòng)物維持恒定體溫消耗的能量越多。 All anisms gain heat from and lose heat to their environment as well as producing heat. A variety of physiological and behavioral mechanisms are used to regulate heat. Despite these mechanisms, the body temperature of an ectotherm varies significantly with environmental conditions. Heat exchange 熱 交 換 所有的有機(jī)體從它們的環(huán)境中得到熱，也將產(chǎn)生的熱散失到它們的環(huán)境中。種種生理學(xué)和行為學(xué)的機(jī)理被用于調(diào)節(jié)體熱。盡管有這些機(jī)理，外溫性動(dòng)物的體溫還是明顯地隨環(huán)境條件而改變。 High temperatures may lead to enzyme inactivation or the unbalancing of ponents of metabolism。 for example, in plants, respiration may proceed faster than photosynthesis, leading to death, however, the most frequent effect of high temperature on ectotherms is dehydration. All terrestrial ectotherms must conserve water but at high temperatures rates of water loss can be lethal. There are large differences between the low temperature tolerances of differing species, associated with the processes of freezing, chilling and hardening. Many are ki
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